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Biomedical subjects

T Ebels

Publications and source records attributed to T Ebels.

63 records · Page 4Linked to original sources
PubMed1988

Doppler mapping of postoperative left atrioventricular valve regurgitation.

Left atrioventricular valve regurgitation often occurs as a postoperative hemodynamic complication from repair of an atrioventricular septal defect. In this study, cross-sectional two-dimensional Doppler flow mapping of the left atrium was used to quantify postoperative regurgitant flow in 29 patients. Its severity and location was related to the shape of the three leaflets of the left component of the atrioventricular valve, especially to the size of the mural leaflet. To identify which leaflet configuration was likely to cause regurgitation, the position of the leaflets was obtained from the parasternal short-axis view and the angular size of the mural leaflet expressed in degrees of an arc. Doppler mapping was performed in the apical four-chamber and the parasternal long-axis views, dividing the left atrium in nine squares in each. Regurgitation was defined as a jetlike systolic downstroke of the Doppler frequency shift in early systole. The angular size of the mural leaflet varied from 38 to 144 degrees (mean 86 +/- 36 SD). Massive regurgitation (six to nine sites) was encountered in seven patients, five with a mural leaflet size of over 110 degrees, one with mural leaflet size between 70 and 110 degrees, and one with a mural leaflet size of under 70 degrees. No or minimal regurgitation was encountered in 10 patients, three having a mural leaflet size of 70 to 110 degrees and seven with a mural leaflet size of less than 70 degrees. These data suggest that massive regurgitation is encountered in patients with large mural leaflets, whereas patients with smaller mural leaflets tend to have no or mild regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1987

Orthodromic pacemaker circus movement tachycardia.

We report on the case of a 33-year-old woman with sick sinus syndrome who had an orthodromic pacemaker circus movement tachycardia (PCMT), with antegrade atrioventricular (AV) conduction and a retrograde pathway by means of a DDD (AV universal) pacemaker. This PCMT was provoked and sustained by premature ventricular contraction-synchronous atrial stimulation (PVC-SAS), which is a new feature for the prevention of antidromic PCMTs. The conditions for occurrence of this tachycardia were: PVC-SAS; atrial undersensing; first degree AV block. Recommendations for prevention of this pacemaker-mediated tachycardia are given.

Adult↗
PubMed1986

Left atrioventricular valve after surgical repair in atrioventricular septal defect with separate valve orifices ("ostium primum atrial septal defect"): an echo-Doppler study.

Left atrioventricular (AV) valve dysfunction is the most frequent major postoperative hemodynamic complication in patients with AV septal defect. The anatomy and function of the left AV valve were investigated in 64 patients with separate valve orifices (ostium primum atrial septal defect) who had survived corrective surgery. M-mode and cross-sectional echocardiograms of the left AV valve were obtained. Doppler flow tracings were obtained at the left AV valve orifice to determine if regurgitation was present. The findings were related to the position of the commissures between the leaflets, the size of the 3 leaflets and the position of the papillary muscles. Left AV valve regurgitation was present in 29 of 51 patients (57%). These patients had a significantly different left AV valve leaflet configuration, characterized by a large mural leaflet and a small inferior bridging leaflet. The size of the superior bridging leaflet is not a determinant factor. Thus, the configuration of the left AV valve in AV septal defect is related to the postoperative functional result. Awareness of the echocardiographic anatomy may influence the surgical approach to this defect.

Echocardiography↗
PubMed1986

The surgical anatomy of the left ventricular outflow tract in atrioventricular septal defect.

The left ventricular (LV) outflow tract (OT) in atrioventricular (AV) septal defect is an important structure that paradoxically is hardly ever seen by a surgeon. The LVOT is prone to develop obstruction following surgical procedures, such as left AV valve replacement, that seemingly do not affect the LVOT itself. We examined 15 hearts with AV septal defects and noted the anatomical boundaries of the LVOT. Additionally, the LVOT was examined microscopically, and it was sectioned to replicate echocardiographic images. A sham operation was performed to show the extent of the proposed resection for AV valve replacement. The mean length of this area was 91.8 +/- 35.5% (range, 28.6 to 167.0%) of the diameter of the ascending aorta in our specimens of the Rastelli A variety. The mean diameter of the LVOT was 68.2 +/- 13.5% (range, 42.9 to 100.0%) of the diameter of the ascending aorta. The posterior wall of the OT can either be resected or widened. Resection seems to be opportune at AV valve replacement, whereas widening could be performed when the OT is intrinsically stenotic. When one fully appreciates the concept of a five-leaflet common valve, it is clear that the length of the OT depends on the extent of adherence between the superior bridging leaflet and the septal crest. In hearts that have two separate AV valve orifices, the OT is fully developed; there is no potential for interventricular shunting ("ostium primum defect"), because the superior bridging leaflet is always tightly adherent to the septal crest. AV valve replacement in these cases is especially hazardous.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta, Thoracic↗
PubMed1984

Anatomic and functional "obstruction" of the outflow tract in atrioventricular septal defects with separate valve orifices ("ostium primum atrial septal defect"): an echocardiographic study.

Left ventricular (LV) outflow tract (OT) obstruction can be treacherous in any form of atrioventricular (AV) septal defect. The properties of the LVOT were investigated echocardiographically in 64 patients with separate valve orifices ("ostium primum atrial septal defect") who had survived corrective surgery. M-mode and cross-sectional echocardiographic (echo) images were made of the LVOT. The degree of malalignment of the aorta with the ventricular septum, the left atrium-aortic ratio, the fractional LV shortening and the diameter of the LVOT were recorded. Fixed anatomical obstruction was found in 3 patients, consisting of muscular bands or abnormal attachment of tension apparatus. Malalignment of the aorta with the ventricular septum was found in 62% of the patients. The diameter of the LVOT was smaller than that of the aortic root in 71% of the cases. The mean diameter of the LVOT was 92 +/- 27% (range 35 to 143%) of the aortic root diameter. Because its walls are mainly muscular, the LVOT constricts during systole. The mean end-systolic diameter of the LVOT was 77 +/- 22% (range 23 to 129%) of the aortic root diameter. Sequential measurements showed that the LVOT constricted gradually, but the velocity of constriction in patients with the most severe narrowing showed a distinct maximum in the first fifth of systole. In conclusion, a series of elements contribute to a potentially perilous arrangement of the LVOT in patients with AV septal defect. This intrinsically narrow tunnel was constricted during systole by its muscular walls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗